Russia has said it will begin to take a "symmetrical response" against US media over measures against its broadcaster, RT (Russia Today).
The US Department of Justice has given the broadcaster until Monday to register as a foreign agent there - otherwise the channel could see its accounts frozen.
RT also says the head of the station could face arrest.
The company says the US Department of Justice sent it a letter in September, claiming it is obligated to register under the Foreign Agents Registration Act (FARA).
The law was first enacted in 1938, and requires people to make "periodic public disclosure of their relationship with the foreign principal, as well as activities, receipts and disbursements in support of those activities."
Russian Foreign Ministry spokeswoman Maria Zakharova told the Rossiya-24 television channel: "I think that our patience that is nearly run out will take some legal shape.
"I don’t rule out it will be done next week".
"As of today, there is understanding that a practical phase of these response measures will begin next week."
RT's editor-in-chief, Margarita Simonyan said on Thursday the timeframe provided for the company is a "cannibalistic deadline."
She previously claimed the channel was being forced into "conditions in which we cannot work" in the US, and that Washington's demand was an attempt to "drive [RT] out of the country."
Ms Simonyan said while RT America will comply with the demand and register as a foreign agent, the company will challenge the decision in court.
And in a statement on its Facebook page, the Russian embassy in Washington DC said: "The Russian side has repeatedly warned that any measures limiting activity of the Russian mass media in the United States will inevitably trigger an immediate symmetrical response, as provided for in the Russian legislation."
"Blatant pressure on the Russian mass media confirms that the United States pursues the course of deliberately hurting our relations.
"We consider its demand as a wish to eliminate an alternative source of information, which is an unacceptable violation of the international norms of free press."
The Russian embassy in Ireland also tweeted links to articles about the move.
It comes just weeks after social media site Twitter announced that it would ban ads from accounts owned by RT and Sputnik.